Unifies mysql and mysql2 casting of booleans

Using the mysql2 adapter, boolean values were sometimes being incorrectly cast
to 't' or 'f'. This changes the cast to match the mysql adapter behavior, ie 1 and 0.

activerecord/CHANGELOG.md

+*   Fix bug when using Mysql2 adapter where in some cases, boolean values were
+    being output in sql as `t` or `f` instead of `1` or `0`. Example:
+
+        class Model < ActiveRecord::Base
+          validates_uniqueness_of :boolean_col
+        end
+        Model.first.valid?
+
+    Previously generated sql:
+
+        SELECT 1 AS one FROM `models` WHERE
+          `models`.`boolean_col` = BINARY 'f' LIMIT 1
+
+    With fix:
+
+        SELECT 1 AS one FROM `models` WHERE
+          `models`.`boolean_col` = BINARY 0 LIMIT 1
+
+    Fixes: #11119
+
+    *Adam Williams*
+
 *   `change_column` for PostgreSQL adapter respects the `:array` option.
 
     *Yves Senn*

activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb

@@ -272,6 +272,12 @@ def quoted_false
         QUOTED_FALSE
       end
 
+      def type_cast(value, column)
+        return super unless value == true || value == false
+
+        value ? 1 : 0
+      end
+
       # REFERENTIAL INTEGRITY ====================================
 
       def disable_referential_integrity(&block) #:nodoc:

activerecord/lib/active_record/connection_adapters/mysql_adapter.rb

@@ -160,12 +160,6 @@ def error_number(exception) # :nodoc:
 
       # QUOTING ==================================================
 
-      def type_cast(value, column)
-        return super unless value == true || value == false
-
-        value ? 1 : 0
-      end
-
       def quote_string(string) #:nodoc:
         @connection.quote(string)
       end

activerecord/test/cases/adapters/mysql2/quoting_test.rb

+require "cases/helper"
+
+module ActiveRecord
+  module ConnectionAdapters
+    class Mysql2Adapter
+      class QuotingTest < ActiveRecord::TestCase
+        def setup
+          @conn = ActiveRecord::Base.connection
+        end
+
+        def test_type_cast_true
+          c = Column.new(nil, 1, 'boolean')
+          assert_equal 1, @conn.type_cast(true, nil)
+          assert_equal 1, @conn.type_cast(true, c)
+        end
+
+        def test_type_cast_false
+          c = Column.new(nil, 1, 'boolean')
+          assert_equal 0, @conn.type_cast(false, nil)
+          assert_equal 0, @conn.type_cast(false, c)
+        end
+      end
+    end
+  end
+end